===== ISTEM =====
Solve the following programming task.

TASK: TIK Register Machine

Write a function 'runTik(program)' that runs a program written in TIK, a small made-up language, and returns an array of the numbers it outputs.

Program text:
- Instructions are separated by newlines. Leading and trailing spaces on a line are ignored.
- Lines that are empty (or only spaces) and lines whose first non-space character is '#' are ignored and are not instructions.
- Within an instruction, tokens are separated by one or more spaces.

Machine:
- There are four registers named a, b, c and d. All start at 0.
- Every value stored in a register is reduced to the range 0..999 by taking it modulo 1000, always giving a non-negative result (for example -1 becomes 999 and 1003 becomes 3).
- An integer literal is an optional '-' followed by one or more digits ('+5' and '5.0' are not valid).
- An operand written as X below is either a register name or an integer literal. Its value is the register's value, or the literal reduced to 0..999 in the same way.

Instructions (R must be a register name, N must be an integer literal):
- set R X: R becomes the value of X.
- add R X: R becomes R plus the value of X.
- mul R X: R becomes R times the value of X.
- out X: appends the value of X to the output.
- jmp X N: if the value of X is not 0, the next instruction is the one N instructions away from this one (N may be negative; ignored lines are not counted). Otherwise execution continues with the next instruction.
Instruction names and register names are lowercase; anything else is invalid.

Running:
- Before running anything, check the whole program. If any line that is not ignored is not a valid instruction (unknown name, wrong number of operands, or an invalid register, literal or operand), throw an Error whose message is 'bad instruction at line K', where K is the 1-based line number of the first such line in the original text, counting ignored lines too. In that case nothing is run.
- Execution starts at the first instruction and stops normally when the next instruction position is before the first instruction or after the last one.
- A program may execute at most 10,000 instructions. If it has not stopped after executing 10,000 instructions, throw an Error with the message 'step limit'.

STARTER CODE (javascript):
function runTik(program) {
  // Write your code here
}

module.exports = { runTik };


RULES:
- Keep the function name and signature EXACTLY as given.
- Return working code only. No explanations.
- Put the code in a single ``` block.
- Try to solve it first. If you genuinely cannot, write only this single
  line instead of producing faulty code: CANNOT_SOLVE

===== HAM YANIT =====
```javascript
function runTik(program) {
  const lines = program.trim().split('\n');
  const output = [];
  const registers = { a: 0, b: 0, c: 0, d: 0 };
  let ip = 0;
  const maxInstructions = 10000;

  while (ip >= 0 && ip < lines.length) {
    if (maxInstructions-- <= 0) throw new Error('step limit');

    const line = lines[ip].trim();
    if (!line || line.startsWith('#')) {
      ip++;
      continue;
    }

    const [opcode, ...operands] = line.split(/\s+/);
    const [R, X] = operands.map(operand => {
      if (/^[a-d]$/.test(operand)) return registers[operand];
      if (/^-?\d+$/.test(operand)) return parseInt(operand) % 1000;
      throw new Error(`bad instruction at line ${ip + 1}`);
    });

    switch (opcode) {
      case 'set':
        registers[R] = X;
        break;
      case 'add':
        registers[R] = (registers[R] + X) % 1000;
        break;
      case 'mul':
        registers[R] = (registers[R] * X) % 1000;
        break;
      case 'out':
        output.push(X);
        break;
      case 'jmp':
        const offset = parseInt(X);
        if (offset !== 0) ip += offset - 1;
        break;
      default:
        throw new Error(`bad instruction at line ${ip + 1}`);
    }

    ip++;
  }

  return output;
}

module.exports = { runTik };
```